Designing steel composition and microstructure to better resist degradation during wheel-rail contact
Lead Research Organisation:
University of Leeds
Department Name: Institute for Transport Studies
Abstract
Abstracts are not currently available in GtR for all funded research. This is normally because the abstract was not required at the time of proposal submission, but may be because it included sensitive information such as personal details.
Publications
Bevan A
(2018)
Judicious selection of available rail steels to reduce life-cycle costs
in Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit
Odolinski K
(2018)
Dynamics in rail infrastructure provision: Maintenance and renewal costs in Sweden
in Economics of Transportation
Ojeda Cabral, M.
(2017)
The relationship between costs and travel time reliability of train operating companies
Smith ASJ
(2016)
Estimating the marginal cost of different vehicle types on rail
| Description | The key achievements from the research project can be summarised as follows: 1. The damage susceptibility of different track sections has been assessed using detailed vehicle dynamics and rail damage modelling to formulate guidelines for deployment of different rail steels. This has resulted in a development of a rail damage susceptibility map for a number of routes and the methodology to generate these maps. 2. A laboratory twin-disc facility has been developed that generates wheel-rail contact conditions that have a closer resemblance to the actual damaging loading conditions seen on track. It is hoped that this test rig form a useful tool for the characterisation of the next generation of rail steels. 3. Detailed metallurgical examination combined with neural network analysis of test results from selected laboratory twin disc test samples has drawn some key breakthroughs in understanding the influence of alloying elements and hardness on degradation of rail steel microstructures. This assessment was completed on a limited number of available samples, tested for RCF resistance on the small-scale twin disc machine located at British Steel, and despite this limitation the research has identified that fragmentation of the pearlitic cementite lamellae and consequently their dissolution during local plastic deformation, is a key microstructural feature differentiating the RCF resistance of steels. Steels alloyed with silicon (as is the case for HP335) resist better the dissolution of cementite, and thereby impart improved resistance to RCF. Vanadium alloyed steels, such as HP335, displayed less plastic deformation and shallower depths of cementite fragmentation than those without vanadium at similar levels hardness. 4. A detailed cost-benefit analysis approach was developed to assess the impact of optimum rail steel grade selection on whole routes. This approach includes a life cycle cost assessment using the industry-standard VTISM tool. 5. New econometric work was conducted to better understand the important yet complex relationship between quality and cost on the railways; taking into account both proactive and reactive elements and building on research carried out in health and energy. 6. In collaboration with Network Rail, the research is supporting the development of guidelines to optimise the selection of rail steel grades taking into account damage susceptibility, vehicle-track characteristics, operational conditions and economic benefits. |
| Exploitation Route | A number of areas of further work have been identified through the research which will now be further investigated as part of a follow-on project commissioned by Network Rail as part of the EU Shift2Rail project, In2Track. These include: • Verification of the research outputs through further twin disc testing and examination of in-service rail samples. • Assessment of the depth of cementite fragmentation in both hypo and hypereutectoid steel rails taken out of track also needs to be undertaken. • Application of the findings of the current research to the optimisation of material selection for switches and crossing. This will complement the detailed modelling work that has already been undertaken to predict the variation in wheel-rail forces and damage susceptibility of different S&C components during previous EU Shift2Rail projects. • The influence of decarburisation on the early initiation of RCF cracks with little subsequent propagation in HP335 steel needs to be examined since there is no objective measure. The research on cost-quality interactions was included in a bid to the Northern Rail Innovation Fund (provisionally approved in 2017) |
| Sectors | Energy,Healthcare,Transport |
| Description | The detailed metallurgical examinations and neural network analysis completed during the research has produced some key breakthroughs in understanding the influence of alloying elements and hardness on the degradation of rail steel microstructures. This has resulting in the publication of two journal articles and the outputs will be further refined during a follow-on project recently commissioned by Network Rail to support the EU Shift2Rail project, In2Track (http://projects.shift2rail.org/s2r_ip3_n.aspx?p=IN2TRACK). A laboratory twin-disc facility has been developed during the research that generates wheel-rail contact conditions that have a closer resemblance to the actual damaging loading conditions seen on track. This test rig will support the future characterisation of current and next generation of rail steels, along with the performance of rail welds and materials for switches and crossings (S&C). This test rig will be utilised during a follow-on project (see above) and there has also been interest from a number of rail manufacturers in using the test rig. A detailed cost-benefit analysis (CBA) has been undertaken to assess the cost impact of optimum rail steel grade selection of whole railway routes. This included the novel application of the UK industry-standard strategic cost modelling tool VTISM. The developed methodology has gained interest from international infrastructure managers and has recently been presented to participants of the 'International Collaborative Research Initiative' (ICRI) into RCF and wear of wheels and rails being coordinated by National Research Centre of Canada (http://icri-rcf.org/). The outputs from the CBA have also helped to quantify the benefits of current Network Rail strategy for the deployment of HP335 rail steel grade (e.g. in critical curves where RCF and wear causes the premature replacement of the rail, in moderate curves to preserve the ground rail profiles and increase the rails resistance to RCF and in tight curves with high rates of wear, where there is a cost savings and operational benefits from applying HP rail across the whole route). An article in the IMechE Journal of Rail and Rapid Transit has been published which summaries the deployment of available rail steels to reduce life cycle costs. Network Rail are also utilising some of the research outputs to develop enhanced guidelines Route Asset Managers (RAMs) to support the optimum selection of rail steels taking into account damage susceptibility, vehicle-track characteristics, operational conditions and economic benefits. New research has also been carried out to better understand the link between cost and quality on the railways, this being presented at the ITEA conference in 2017. A journal paper published from this work: Smith, A.S.J. and Ojeda Cabral (2022), Is higher quality always costly? Marginal costs of quality: theory and application to railway punctuality, Transportation Research Part A: Policy and Practice. https://authors.elsevier.com/a/1ebam3Rd3ux-NC |